Cleansing means for metal and metal alloys



Patented Sept. 27, 1938 CLEANSING MEANS 1 R METAL AND METAL ALLOYS Willi Claus, Berlin, Germany, assignor to Metallochemische Fabrik, A.-G., Berlin, Germany, a corporation of Germany No Drawing. Application March 26, 1937, Serial No. 133,193. In Germany March 30,1936

2 Claims,

not merely at the surface thereof and yet a/ccomplishes this result without resort to dipping apparatus.

Where a solid cleansing means of this type is used, whether in small particles orin the form of pellets of relatively low specific weight compared to that of the bath to be treated, the difficulty results that the reaction with the metal bath either occurs onlysubstantially at the sur face and 'so with negligible effect with respect to the mass of the material to be treated, or such means would necessitate the useof special dipping apparatus for submersioninto the bath. The

latter procedure would have the disadvantage that some reaction might occur. in the molten bath with respect to the dipping apparatus, with consequent adulteration of the metal or alloy and moreover material loss of metal would result due to adhesion thereof over the entire surface of the dipping apparatus followed by oxidation of the same after removal from the bath. The objections to taking up of iron for instance in aluminumalloys is known to those skilled in the art.-

'According to the present invention the pellet is made of compacted pulverulent material of specific gravity so high as to sink to the bottom of the bath when introduced thereinto and as the 40 pellet is consumed, vigorous agitation occurs from the bottom upward, thereby to carry out the cleansing action throughout the entire volume of the bath. For this purpose a light medium may be used which performs a direct reducing or deoxidizing'action upon the molten metal, mechanically combined with a heavy medium that imparts to the pellet the high specific gravity desired.-

. In carrying out the invention in practice, the active reaction material, usually. an inorganic cleansing-salt of the typeknown to those sldlled in the art, is combined with a flller'which serves as' weighting means to impart the desired high specific gravity. If desired, the filler or weight- 5 ing means'may itself perform a useful reaction provide a cleansing means of the type set forth,

.and carry on the cleansing operation of the molten bath to a degree. I would usually be a metal of melting point lower than the bath but of specific gravity when compacted, higher than the bath. For instance, for pellets used in cleansing aluminum or aluminum alloys, lead may be incorporated in the pellet with the inorganic cleansing salts the said constituents being compacted together under pressure. Desirably the inorganic cleansing saltmay be 40% by weight and the lead 60% by weight of the pellet. The lead will serve not only as the weighting means, but also to entrain any aluminum oxide formed in the bath which becomes separated and eliminated from the bath.

The inorganic cleansing salt may be any salt, desirably a halogen salt, such for instance as beryllium chlorid, lithium fluorid etc., which will release. gases such as nascent chlorine as it becomes consumed under the heat of the bath, such gas permeating the mass and in its upward course through the surface thereofycombining with or entraining and levitating injurious gases which, if left in the bath, would result in objectionable oxides, nitrides, carbides and sulphides. After completion of the reaction, all these impurities will collect as a dry powder or ash upon the sur-.

face of the bath, from which they may be readilyscooped off after the reaction has been completed. I

If desired, during the interval that the reaction is occurring, the temperature of the bath may be reduced by the introduction thereinto'of clean blocks of metal until the bath, which desirably .has a temperature of between 740 and 750 C. at the time that the pellet is introduced, has been reduced to the casting temperature of about'IOO" C. 'For best results, the temperature would of course be controlled by a suitable pyrometer.

. Where in exceptional cases,'an especially large amount of ash results from the treatment, it may be advisable to treat the same with a few grams of zinc chloride in order to remove from the ash The weighting means any remnant of useful metal that might have become incorporated therein.

A pellet of 33% grams suffices for an aluminum or aluminum alloy bath of 30 kilograms. Where a relatively large vessel requiring more than one of the pellets is filled to the rim it is advisable to introduce these successively in order to avoid too vigorous agitation.

As many changes could be made in the above means and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is.

intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A cleansing material for molten aluminum baths, comprising compacted pellets composed of active halogen salts and of lead which has a melting point lower than that of the bath, whereby the pellet when introduced will sink to the bottonmf the bath and will become consumed therein with the evolution of gas that will combine with and entrain gaseous impurities to the surface, while the lead will serve to entrain and carry to the surface any aluminum oxide that might be formed. r

2. The pellet of cleansing material as claimed in claim 1, composed of approximately 40% of inorganic halogen cleansing salt and 60% of lead powder.

CLAUS. 

